基于生产力维持的紫色土容许土壤流失量研究
文献类型：学位论文
| 作者 | 杜树汉 |
| 学位类别 | 博士 |
| 答辩日期 | 2012-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 刘刚才 |
| 关键词 | 土壤侵蚀 土壤生产力 容许土壤流失量 紫色土 |
| 学位专业 | 自然地理 |
| 中文摘要 | 土壤侵蚀严重地损害土壤生产力，对世界食物生产能力和全球食物安全构成严重的威胁。容许土壤流失量(T值)是划分侵蚀区与非侵蚀区的判别标准，是制定水保方案和评价水保措施有效性的依据。但是，容许土壤流失量的研究还十分薄弱，特别是基于土壤生产力维持的容许土壤流失量，目前还没有试验研究报道。本研究结合我国实际和紫色土的特性，在一个典型的紫色土小流域内，进行连续田间观测实验，并配合室内分析实验，研究紫色土地区土壤侵蚀对土壤生产力的影响特征与影响机制；同时，研究土壤侵蚀与土壤生产力之间的定量关系，并探讨土壤生产力维持约束条件下确定容许土壤流失量的试验实测方法；取得的主要结论如下： (1) 土壤侵蚀对生产力影响研究方面，我们采取小区和盆钵实验方法，通过研究不同土层厚度（即不同土壤侵蚀程度）对作物生长发育的影响，来揭示土壤侵蚀对生产力的影响。结果显示，无论是小麦，还是玉米，它们的生长发育的生物性状都与土层厚度呈显著（P<0.05）的正线性关系。小区试验结果表明，土层厚度对作物产量也有不同程度的影响。盆栽试验的结果与小区的有一致性规律，土层厚度同样对作物的千粒重和产量有明显的影响。在研究区，每侵蚀10cm土层，玉米将减产10.8%（约11%），小麦将减产10.6%。反过来，玉米每减产1%的产量，可以侵蚀0.92cm土层，而小麦的可以侵蚀0.94cm土层。从侵蚀对生产力影响的定量关系分析，无论是小麦还是玉米的减产率，与侵蚀土层厚度即侵蚀程度都呈极显著指数增加关系。 (2) 侵蚀对生产力影响机制研究表明，土层愈薄引起的径流，无论是表面径流还是壤中流，都愈多。流失的径流愈多，土壤流失的水分也愈多，必然导致作物减产。即侵蚀引起水分流失增多导致作物减产，生产力下降。不同土层厚度下侵蚀泥沙中的有机质和有效氮磷钾的含量较原土的明显高。侵蚀引起养分流失导致作物减产，生产力下降。侵蚀会使土壤出现沙化结构破坏等退化特征，进而导基于生产力维持的紫色土容许土壤流失量研究致生产力下降。侵蚀造成土层变薄，水热变化快，不利于作物生长，由于土壤肥力是由水肥气热等因素决定的，侵蚀引起土壤肥力的下降，从而使土壤生产力下降。 (3)通过研究施肥等投入对生产力的影响，结果表明: 生物量和产量都与施肥水平呈正线性关系, 肥料的产量效应需要一定的土层厚度。 从研究区的历年作物产量趋势分析表明：生产技术促使单产增加量会是愈来愈小，单产递增率呈指数递减趋势，单产不仅受生产投入、管理等的影响，还受其它不可控制的自然因素的影响。 (4) 根据上述研究，我们提出了基于生产力维持的容许土壤流失量确定的5项基本原则和相关确定方法。根据研究区单产（土壤生产力）的递增趋势和我国的人口增长趋势和预测，该区土壤生产力的年递增率允许减少0.1%。根据基于生产力维持的容许土壤流失量确定的原则和生产力减产与侵蚀之间的定量关系（土壤生产力每减产1%有0.92cm的土壤被侵蚀掉），当紫色土的土层厚度<60cm时，土壤生产力没有正常性和可增长性，为保障这种土壤的正常生产力，其T值为0；当土层>60 cm时，可容许侵蚀0.092cm/年的土壤，其T值为1104 t·km-2·a-1 (假设紫色土的容重为1.2)。 本研究T值确定方法和基于成土速率的确定方法,两种方法确定的T值比较接近，相差仅约10%。因此，基于土壤生产力水平确定的T值约为1100 t·km-2·a-1是可信的。为简单和应用起见，四川紫色土区的T值确定为1000 t·km-2·a-1是比较可行的。 |
| 英文摘要 | Soil erosion seriously damages the soil productivity, so it has serious threat on food production capacity and global food security. Soil loss tolerance (T value) is the criterion for judging non-excessive erosion and erosion areas, and the valid basis of making soil and water conservation scheme and efficiency evaluation of soil and water conservation measures. This study combined the fact of our country and the characteristics of purple soil, and carried out continuous field observation experiment on the purple soil in a typical small watershed. The study mainly concerned on the relationship between soil erosion and soil productivity, and on characteristics of soil erosion affecting soil productivity in purple soil area, and its effect mechanism, and finally aimed at finding a method to determine soil loss tolerance under constraint condition of soil productivity maintenance. The main results were found as follows: (1) With regard to soil erosion influence on productivity, the field and pot experiment were conducted to investigate the effect degree of different soil depth’s (i.e., different soil erosion degree) on crop growth and the effect of soil erosion on productivity. The results showed either wheat or corn, their growth indicators were significantly (P < 0.05) positive linear relationship with soil thickness. Field experiment results found that the effects of soil thickness on crop yield are in different degree. Results of pot experiment showed a consistent conclusion that soil thickness have obvious effects on the kilo-grain weight and yield of crops. In study area, eroding each 10cm soil thickness, corn would reduce the production of 10.8% (about 11%), wheat’ reduction of output is 10.6%. By quantitative analyzing the erosion’s affection on productivity, crops’ yield reduction rate significantly and exponentially increased with soil erosion degree (eroded soil depth). (2) Research about the mechanism of erosion affecting soil productivity. Results showed that, the thinner soil caused the more runoff, both surface runoff and subsurface flow. The more runoff loss, would inevitably lead to the reduction of crop yield. Namely erosion caused increasing water loss lead to crop yield reduction, and resulted in soil productivity descending. Under different soil thickness, soil organic matter, available nitrogen, phosphorus and potassium content in eroded sediment were significantly higher than that in the original soil. Indicate that erosion caused nutrient loss leading to the reduction of crop output and soil productivity decrease. Meanwhile, Erosion made soil sandy and degradation, such as soil structural damage, and consequently decreased soil productivity. Soil erosion as well as induced soil thinning, and soil moisture and temperature change quickly, which is not conducive to the growth of crops, due to the soil fertility is determinated by water and heat and other factors. In other words, erosion caused soil fertility decline, consequently the soil productivity decreased. (3) Through investigated the impact of fertilization on soil productivity, the results showed that both the biomass and yield are a positive linear relationship with fertilization level, and the fertilizer’s yield efficiency need a critical soil depth of 60 cm. statistic analysis found that, in the study area, crop yield showed an increasing trend over the years, but the annual increasing rate slowed and stabilized to approximately 1%, and the unit yield increasing rate has exponentially declined in recent years . Yield not only influence by the input of fertility, management, but also by other uncontrollable natural factors. (4) Concerned on the above results, we suggested the five basic principles and its methods for the determination of soil loss tolerance based on the maintenance of productivity. After analyzing the increase in the local soil productivity and the requirements for sustainable social development, the soil productivity reduction tolerance was found to be 0.1%. Based on the basic principles and the quantitative relationship of soil productivity to soil erosion degree (with a 1% reduction in crop yield, the soils planted with corn were eroded by 0.92 cm), when the thickness of purple soil is less than 60cm, soil productivity is not sustainable, T value is ought to be 0 to ensure the soil’s normal productivity; when the soil thickness is deeper than 60cm, soil productivity reduction can tolerate 0.1%, namely eroding 0.092 cm soil depth each year is allowable, therefore, T value is 1104 t·km-2·a-1 (assuming the purple soil bulk density is 1.2). The two determination method of T value determination, ones based on soil productivity in this study and ones based on soil formation rate, their results is approach with only about 10% difference. Therefore, based on soil productivity level, the T value of 1100 t·km-2·a-1 is credible. For simple and convenient application, the T value in purple soil areas of Sichuan province determined as 1000 t·km-2·a-1 is feasible. |
| 语种 | 中文 |
| 公开日期 | 2012-12-21 |
| 源URL | [http://192.168.143.20:8080/handle/131551/4619]  |
| 专题 | 成都山地灾害与环境研究所_山地灾害与地表过程重点实验室 |
| 推荐引用方式 GB/T 7714 | 杜树汉. 基于生产力维持的紫色土容许土壤流失量研究[D]. 北京. 中国科学院研究生院. 2012. |
入库方式： OAI收割
来源：成都山地灾害与环境研究所
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